This invention relates to the field of preparing food products in shirred, tubular casings and enclosing the products in netting. One method generally used in the industry is to pump food products, such as sausage meat, whole muscle meats, or otherwise, through a product horn. The meat products are forced into an edible film and then into netting. The food products to be packaged will expand and push the film through the netting. After processing, such as smoking or cooking, the netting will be removed, leaving a dimpled appearance on the food products that is considered pleasing to consumers. The edible casing will prevent the netting from sticking to the meat, so upon removal of the netting a clean appearance of the meat is maintained. (There is no reason why the invention is limited to meat; it can be used for cheese or vegetarian sausage or anything else for which a dimpled appearance is desired.) This method is illustrated in U.S. Pat. No. 4,910,034 to Winkler, Process for the Production of Meat Products, and its divisional, U.S. Pat. No. 4,958,477, the disclosures of both of which are incorporated herein. As can be seen from FIG. 4 of those two patents, there are three coaxial tubes. The sausage meat or other ingredient is pumped into the smallest diameter tube; the middle tube forms the edible casing into a tube; and the outer tube (the “netting tube”) holds the netting.
The tubular netting used in this process arrives from the manufacturers in a flattened state and wrapped circumferentially on a disposable cylinder. In order to be used as described above, the netting has to be shirred onto a temporary netting tube. This shirring process, or “rucking”, involves placing the netting coaxially onto the netting tube. There is an advantage to being able to maximize the amount of netting placed on the netting tube, in that downtime to change or to reload netting tubes causes disruptions and inefficiencies in the process. Once the netting has been shirred onto the netting tube, the tube is placed on a sausage making machine for extrusion of sausage, as described in the '034 and '477 patents and as illustrated in, for example, FIG. 7 of those patents.
In the prior art, to ruck netting onto a netting tube, the netting tube is caused to reciprocate vertically, such as by use of an air cylinder. The netting is stretched over the tube. A plurality of spring-loaded fingers secured to a bracket surround the netting tube circumferentially. These fingers are normally in a horizontal position. Downward force moves them down; the springs cause them to snap back to the normal horizontal position when the force is removed. Accordingly, the fingers carry the netting downward during the upward stroke of the tube, and slide over the netting during the downward stroke of the tube. The reciprocating motion of the netting tube therefore causes the netting to be shirred onto the netting tube. This prior art is described in, for example, U.S. Pat. No. 5,273,481 to Sullivan, Net Rucker, the disclosure of which is incorporated herein. Note that only one layer of netting is shirred onto the netting tube by this method.
A prior art improvement is to add a second tube, which fits coaxially over the netting tube. The netting is stretched over the second tube. As the netting is carried over the second tube, the second tube rises in relation to the netting tube and the netting is shirred onto the netting tube, in the space between the base of the netting tube and the now-rising second tube. More netting can be shirred onto the netting tube in this manner, as compared to the prior art method of the previous paragraph, because multiple layers can be shirred, thereby rucking more linear feet of netting per length of netting tube. However, the netting is not shirred particularly neatly by this method. It bunches up and is wavy. The generally unkempt appearance of the netting on the tube is displeasing to prospective purchasers of the equipment. Additionally, and more importantly, the lack of neatness, caused as it is by a lack of uniformity, prevents shirring as much netting onto the tube as may be hoped for.
This prior art improvement used a second tube with a larger inside diameter than the outside diameter of the netting tube. Accordingly, a tube cap is inserted into the top of the second tube, to keep the second tube moving coaxially to the netting tube, and to allow the netting to slide smoothly over the second tube. A coaxial ring in the bottom of the second tube keeps the second tube coaxial to the netting tube, and will push the netting downward on the netting tube.
Although this prior art improvement increases the amount of netting that can be rucked onto a netting tube, further increases in this amount are desirable to users of the apparatus. Additionally, newly-developed devices attach to the output end of the netting tube during sausage making and allow the netting to slide off the netting tube in discrete, predetermined lengths, such as U.S. patent application Ser. No. 11/553,757, Apparatus and Method For Forming Tubes In Nets, filed Oct. 27, 2006, the disclosure of which is incorporated herein. These newly-developed net deruckers require a clear space on the end of the netting tube, a space greater than the length of sausages to be made, further limiting the amount of netting that can be rucked onto the netting tube. Accordingly, the use of a net derucker further increases the need for maximizing the amount of netting that can be rucked onto a netting tube of given length. (Please note that more netting can be rucked onto a netting tube simply by increasing the size of the netting tube, but this option is not available or, at best, is impractical, for users with limited space.)
One solution has been to provide an annular space defined by the tube ring, the netting tube, and the second tube, as described in U.S. Pat. No. 7,051,415 to Pinto, Net Rucking Apparatus and Method, the disclosure of which is incorporated herein. This solution works well but there is always a need for rucking more netting onto a tube and for rucking the netting more neatly onto a tube. The present invention meets this need.